Ribbon lift mechanism



Dec. 29, 1959 w, wHlPPO 2,919,008

RIBBON LIFT MECHANISM 3 Sheets-Sheet 1 Filed Dec. 2'7, 1957 WALTERB.WHIPPO ATTORNEY Dec. 29, 1959 w. B. WHIPPO 2,919,008

RIBBON'LIFT MECHANISM Filed Dec. 27, 1957 5 Sheets-Sheet 2 3Sheets-Sheet 3 Filed Dec. 27, 1957 FIG.3I

United States Patent tional Business Machines Corporation, New York,N.Y., a corporation of New York Application December 27, 1957, SerialNo. 705,601

.6 Claims. (Cl. 197-157) This invention relates to a typewriter ribbonmechanism and more particularly to a device for lifting a ribbon from aposition below the print line, variable distances upwardly, into theprint line.

'It iscommon practice in the typewriter art to have the ink ribbon restat a position below the print line to leave the print line visible. Itis the usual practice to have 'a ribbon lift mechanism which is actuatedeach time a key is operated to lift the ribbon and interpose it betweenthe platen and the actuated type bar. It also is a common expedient tolift the ribbon variable distances for color control or for utilizingdifferent portions of single color ribbon or to inhibitlifting theribbon during stencil operations.

It is the principal object of this invention to provide an improvedribbon lift mechanism.

A further object of this invention is to provide an improved ribbon liftmechanism having a plurality of lift positions.

Another object of this invention is to provide an improved mechanism forselecting the desired extent of lift.

Still another object of this invention is to provide 'an improvedmechanism for translating a predetermined range of movement of a liftelement selectively'to variable ranges of movement'of aribbon holder.

Yet another object of this invention is to provide a novel device forsnubbing the ribbon guide at the limit of its high lift position inwhich position it attains its greatest acceleration.

Another object of this invention is to provide a ribbon lift mechanismadapted for movement longitudinally of the platen during a serialprinting operation.

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of example, the principle of the invention andthe best mode, which has been contemplated, of applying that principle.

'In the drawings:

Figure 1 is a side elevation partly in section.

Figure 2 is a perspective view.

Figure 3 is a plan view.

Figures 4, 5 and 6 are partial plan views showing successive positionsof a selection device.

Referring to Figure 1, a ribbon lift mechanism, generally designated 10,is mounted on a carrier 12of the type illustrated in a copendingapplication, Serial No. 653,806, filed April 19, 1957, on behalf of LeonE. Palmer, for use with a single print element typewriter wherein theplaten is stationary and the single print element is moved along theplaten to successive print positions. "In the embodiment shown herein,the ribbon llift mechanism moves with the print head across the platen,however, the ribbon lift mechanism could be stationary for use with aconventional typewriter in which the platen moves to successive printpositions.

As described in the above cited application, a shaft 14' i's rotatedonce for each print stroke and operates througha-ca'm (not shown) tothrow'aprint head'1'6 and a ribbon 18 against a platen 20. The ribbon IS-is contained in a cartridge 21 mounted on the carrier 12. The cartridge21 is shown in detail in copending application Serial No. 704,195, filedDec. 20, 1957. A lift cam 22 fixed to the shaft 14 actuates a lift c'amfollower 24, having a U-shaped cross section, which through a mechanismdescribed hereinafter, lifts the ribbon 18 to interpose it between theprint head and the platen.

The plan view of Figure 3 shows the configuration of the carrier 12 inwhich two rods 26 and 28 are pivotally mounted (see Fig. 2 also). AU-shaped member comprising two lower lift arms 32 is welded along itsbase section 30 to the rod 26. A second U-shaped member is welded to therod 28 and comprises upper lift arms 34. Each upper lift arm 34 and thecorresponding lower lift arm 32 form opposite sides of parallelograms. Athird side of the two parallelograrns is formed by members 36 fixed tothe rod 26 and pivotally engaging the rod 28. The fourth side of theparallelograms is formed by two ribbon guides generally designated 38which comprise the upright arms of a U-shaped member 40. The upper andlower lift arms pivotally engage the ribbon guides 38. Each ribbon guide38 comprises a side element 41 having an upper'flange 42 to confine theribbon 18'from above, afront element 44 to confine the ribbon from thefront, a rear element 46 to confine the ribbon from the rear, and alower flange 48 to support the ribbon from below. A phantom section ofribbon 18 is shown in the ribbon guides in Figure 2.

The lift cam follower 24 is pivotally mounted on the carrier 12 by astud 50. The cam follower has an extension '52 which is connected by atension spring 54 to the left hand lower lift arm 32.' The spring 54acts to hold the cam follower 24 against the cam 22. The two sides ofthe U-shaped lift cam follower 24 each contain a slot 56 through which acontrol arm 58 extends. The control arm 58 has a turned up end 59 toretain the arm in the slots 56. The control arm 58 is pivotallyconnected to a selector wheel cam follower 60, the cam follower beingpivotally mounted by a stud 62 on a bracket '64 fixed to the carrier 12by nuts 66 and bolts 68, Figure 1.

A selector wheel 70 having a cam 72 formed integral therewith isrotatably mounted by 'a pivot 74 on the bracket 64. The selector wheel70 is marked at degree intervals with the letters S, L, M and Hcorresponding, respectively, to Stencil, Low Lift, Medium Lift and HighLift. A lug 76 on the cam follower '60 follows the surface of the cam 72when the Wheel 70 is rotated and moves the end of the control arm 58 "topositions in the slot '56 required to accomplish the stencil, low lift,medium lift and high'lift operations. The corresponding positions havebeen indicated on the left hand lower lift arm 32 for ready reference.Figures 3, 4, 5 and 6 illustrate the relationship between the positionof the cam 72, the cam follower 60 and control arm '58. The control arm58, in Figures 2 and 3, is adjusted for medium lift as indicated by theM on the whe'el70 opposite the cam follower lug 76. The wheel 70 isdetented selectively in each of the four positions by a "conventionaldetent device (not shown) which may be, for example, a spring biasedball in the wheel'7 0 engageable "with detent notches I (not shown)spaced at 90 degree intervals in-the bracket 64.

The :ca'r'n follower 24 is lifted through thesame range of movement eachtime the cam 22 is rotated. With the end '59 of the control arm 58 inthe S (stencil) position directly over the pivot 50, Figure 2, thecontrol arm is not raised at all when the follower 24 is moved throughits range of movement. When the end 59 is in the L (low) position of theslot 56, the arm '58 is raised a certain increment designated as an L(low) increment which raises the ribbon inch; when the end 59 is in theM (medium) position, the M increment of movementisidouble the Lincrement and raises the ribbon inch; and when the end 59 is in the H(high) position, the H increment of movement is triple that of the Lincrement and raises the ribbon inch. The movement of the control arm 58raises the ribbon or inch to effect printing through the lower part,middle part or upper part of the ribbon respectively.

The control arm 58, driven by the cam follower 24, imparts a liftingmotion to the lift arms by pushing upwardly on the left hand lower liftarm 32 at a point between the two arms of the U-shaped cam follower 24.As described-hereinbefore, each lower lift arm 32 and the correspondingupper lift arm 34 form opposite sides of a parallelogram, so that whenthey lift the corresponding ribbon guide 38 which forms a third side ofthe parallelogram, the ribbon 18 remains vertical without the use ofguide posts to restrain the guide 38 from bending under ribbon tension.A compound lever is formed by the control arm 58, the cam follower 24and the left hand lower lift arm 32. As the cam follower 2-4 is pivotedabout the pivot 50, the arm 58 is raised and, bearing against the lefthand lower lift arm 32, pivots both lower lift arms about the axis ofthe rod 26, thereby raising the opposite end of the lower lift arms andthe ribbon guides 38.

A scissors action between the cam follower 24 and the lower lift arm 32results in a component of force tending to rotate the selector wheel camfollower 60 in a clockwise direction, thereby holding the lug 76 againstthe cam 72. The spring 54, in addition to holding the cam follower 24against the cam 22, holds the control arm 58 against the cam follower 24and the left hand lower lift arm 32 against the control arm.

In the high lift position, the lift arms achieve their greatestacceleration and it is desirable to limit the upward movement. To avoidovertravel of the liftarms at this point, the corresponding upper andlower lift arms, which form opposite sides of parallelograms, are sospaced as to come in contact at the desired upper limit of the high liftstroke as the parallelograms become more distorted and the oppositesides approach a single plane.

While there have been shown and described and pointed out thefundamental novel features of the invention as applied to a preferredembodiment, it will be understood that various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in the artwithout departing from the spirit of the invention. It is the intentiontherefore, to be limited only as indicated by the following claims.

What is claimed is:

1. A device for moving a ribbon vertically relative to a point ofcontact between a print element and a platen comprising, in combination,a ribbon guide, a supporting frame spaced horizontally from said ribbonguide, a pair of arms pivotally connected at opposite ends to saidsupporting frame and said ribbon guide at points spaced vertically equaldistances, a lever pivotally supported at one end, means including a camfor swinging said lever about its pivot, an element slidably engagingopposing surfaces on said lever and one of said arms for swinging thelatter in response to a swinging of said lever, and means for movingsaid element to selected points along said lever for varying theswinging of said arms.

- 2. A printing device comprising, in combination, a platen, a ribbon,at least one print element, operable for printing contact with saidplaten along a predetermined print'line, means movably supporting saidribbon and operable for interposing said ribbon between said printelement and said platen at said print line, said supporting meanscomprising at least one lower lift arm pivotally mounted at one end andpivotally supporting a ribbon guide at the other end, an upper lift armcorresponding to said lower lift arm, pivotally mounted at one endadjacent said pivotal mounting of said lower lift arm and pivotallyjoining said ribbon guide at the other end, said four pivot pointsforming the vertexes of four angles of a parallelogram, means includinga lever operable for raising said lower lift arm and consequently saidribbon guide to the extent that said parallelogram is collapsed withopposite sides approaching a common plane and engaging one another witha snubbing action, and means for operating said lever.

3. In a typewriting machine, the combination of a platen, a type elementoperable for printing engagement therewith, a rotatable eccentric cam, acam follower pivotally operable by said cam, a frame member, at leastone lower lift arm pivotally mounted at one end to said frame member, aribbon guide pivotally supported at the other end of said lower liftarm, an upper lift arm pivotally mounted in said frame member and saidribbon guide above and parallel to said lower lift arm, said upper andlower lift arm forming two opposite sides of a parallelogram, said framemember and said ribbon guide forming the other two sides, and meansoperatively engaging said cam follower and saidlower lift arm fortranslating pivotal movement of said cam follower to pivotal movement ofsaid lower lift arm at said pivotal mounting in said frame memberthereby lifting said ribbon guide and interposing said ribbon betweensaid type element and said platen.

4. The invention of claim 3 including means selectively operable forshifting the point of engagement of said engaging means whereby theextent of lift of said lower lift arm and said ribbon guide by thepivotal movement of said cam follower is .varied.

5. The invention of claim 4 wherein said selectively operable meanscomprises a rotatable irregular cam, a bell crank having one end adaptedto follow the surface of said cam, and a control arm having one endoperably connecting said cam follower and said lower lift arm, saidcontrol arm being shiftable selectively in accordance with the rotationof said irregular cam.

6. A printing device comprising, in combination, a platen, a ribbon, aprint element movable to successive print positions along said platenand operable for printing contact with said platen, means mounting saidribbon for movement with said print element, means movably supportingsaid ribbon and operable for interposing said ribbon between said printelement and said platen at said print line, said supporting meanscomprising at least one lower lift arm pivotally mounted at one end andpivotally supporting a ribbon guide at the other end, an upper lift armcorresponding to said lower lift arm, pivotally mounted at one endadjacent said pivotal mounting of said lower lift arm and pivotallyjoining said ribbon guide at the other end, said four pivot pointsforming the vertexes of four angles of a parallelogram, means includinga lever operable for raising said lower lift arm' and consequently saidribbon guide to the extent that said parallelogram is collapsed withopposite sides approaching a common plane and engaging one another witha snubbing action, and means for operating said lever.

References Cited in the file of this patent UNITED STATES PATENTS LattaSept. 21, 1909

